by Richard Wolf, USA TODAY

by Richard Wolf, USA TODAY

The high court ruled unanimously that a Florida police officer's use of a drug-sniffing dog to search a truck during a routine traffic stop was appropriate, even though the drugs found were not what the pooch was trained to detect.

Justice Elena Kagan wrote the unanimous opinion for the court â?? and for Aldo, a retired drug-detection dog. "The record in this case amply supported the trial court's determination that Aldo's alert gave (Canine Officer William) Wheetley probable cause to search the truck," she said.

The case was one of two involving drug-sniffing dogs heard on Halloween. In the other case, a dog was used to sniff for drugs on the doorstep of a private home. While the court did not decide that case Tuesday, justices were far more skeptical of the legality of that search during oral arguments.

At the time, the justices seemed amenable to the use of drug-sniffing dogs in general, without quarreling about their training and certification, in order to determine "probable cause" of drug presence. But when the issue arrived on their doorstep, their reaction changed. As a result, they appeared inclined to split the difference.

Several justices had seemed likely to accept the expertise of dogs with documented training to sniff out contraband, rather than demanding case-by-case evidence of their reliability. That was demonstrated by the unanimous decision Tuesday.

Kagan noted that the police officer first encountered a nervous driver, Clayton Harris, and an open beer can. Then Aldo "alerted" at the door handle of the car, giving probable cause for a search. But the search didn't turn up drugs that could be sniffed; instead, ingredients for manufacturing methamphetamine were found, and Harris was arrested.

In ruling for Aldo's competence, the court reversed a decision by the Florida Supreme Court that had required comprehensive documentation of Aldo's "prior hits and misses," Kagan wrote. More important than any hit or miss, she said, was "the totality of the circumstances."

During the other argument in October, the justices drew a proverbial line at the entrance to private homes, arguing that crime-fighting dogs at one's doorstep are far different from trick-or-treaters.

The canines in question â?? Aldo and fellow retired drug detection dog Franky -- weren't in court for the spectacle. But that didn't stop the justices from discussing their qualifications, motives and behavior.

Police "have every incentive to train the dog well," said Justice Antonin Scalia, questioning the Florida court's demand for detailed training, certification and field performance records in Aldo's case. The liberal justices appeared less trusting of a dog's nose but similarly wary of using courts to determine each dog's qualifications.

On the other hand, Scalia and Justice Anthony Kennedy appeared to align with the court's four liberals against Franky, who detected marijuana in a Miami grow house only after spending several minutes sniffing around the front door. Kagan called that "a lengthy and obtrusive process." Justice Ruth Bader Ginsburg said it could lead to random searches of "any home, anywhere."

Both cases hinge on the Fourth Amendment's protection against unreasonable searches -- a protection the high court held in high esteem during its last term, when it ruled unanimously that police should have obtained a warrant before placing a GPS device on a drug suspect's car.

Although modern technology didn't exist when the Founders wrote the Bill of Rights, dogs certainly did -- and they have been used reliably by police for a number of causes, including the search for victims of Superstorm Sandy, which occurred just days before oral arguments.

"Scotland Yard used dogs to track Jack the Ripper," said Gregory Garre, who represented Florida law enforcement in both cases.

"These dogs are quite reliable," agreed Joseph Palmore, representing the U.S. Justice Department, which sided with the state.

But Glen Gifford, an assistant public defender representing one of the defendants, begged to differ. "Dogs make mistakes," he said. "Dogs err."